Made from high-carbon steel and processed through a unique carborizing heat treatment that actually adds carbon to the metal. More carbon on the metal means a harder cutting surface. Blades hold a razor sharp edge that will endure prolonged use and more sharpening treatments. Each Andis Ultra Edge Blade is sharpened to exact quality standards and is hand tested before it is shipped. Blades have a Rockwell Hardness rating of 65. Blade fits Andis, Conair, Oster, and Wahl detachable style clippers. Size 5 Skip Tooth Blade has a 1/4" blade cut.